Improvement in separating oleic and stearic agios



UNITED STATES JAMES S. GWYNNE, OF PITTSBURG, PENNSYLVANIA.-

IMPROVEMENT IN SEPARATING OLEIC AND STEARIC ACIDS."

Specification forming part of Letters Patent No. 4,735, datedSeptemberS, 1846.

To'allwhom it may concern: a

Be itknown that I, Janus S. GWYNNE, of Pittsburg, in the county ofAllegheny and State of Pennsylvania, have invented a new and usefulImprovement in the Method of Separating the Oleic from the Stearic Acid,with a view to obtain stcaric acid for the manufacture of candles; and Ido hereby declare that the following is a full, clear, and exactdescription-of my said improvement.

It is unnecessary for me to describe the process by which the tallow,lard, 860., from which it is desired to obtain the stearic acid areresolved into their component parts of stearic, oleic, and margaricacid, so as to allow of their separation by mechanical means, as this isfully described in the books, and is well known to those skilled in theart of making what are termed stearie-acid candles. I propose to begin,therefore, by describing the process of mechanical separation asemployed to the best of myknowledge and belief up to thetime when theinvention which I am now aboutto patent was put into use.

The mixture consisting of the stearic, oleic, and margaric acids isfirst placed in bags or folders of cotton or hemp and laid in strataalternating with iron plates, to the faces of which flats or mats ofcoarse horse-hair are fastened, the whole forming a mass or pile ofabout two feet square and as deep as may be required by the quantity tobe pressed. This is then placed under the hydraulic or other press toreceive the cold press, as it is tcrmedthat is, a pressure verygradually and slowly increased 'during several days, the effect of whichis to express all that portion of the oleic acid which is fluid at thetemperature of the atmosphere. The mass is then taken apart, remelted orreground, or both, and reconstructed, so to speak-that is to say, puttogether again in the same manner, except that now the iron plates aresometimes heated to a degree sufficient to melt the oleic acid, whichmelts ata temperature varying from 80 1:0,130 of Fahrenheit, but notsufficient to melt the stearic acid, which cannot be melted at a lowertemperature than 158. The mass thus preparedis placed in thepress,whereit is surrounded by an apparatus varying in description, intowhich steam is admitted for the purpose of keep ing up theheat of themass during the operation Sometimes this apparatus aloneis used, theiron plates not being previously of pressure.

heated. The pressure is then applied'and continued until the oleic acidno longer flo wsfrom the'mass. This is called the hot-pressure, andoccupies from a few hours to several days, according to circumstances.The cold-pressure already referred to occupies from one to six days,also according to the state of the.

weather and circumstances. Now, it will be at once perceived that thereis here a greatloss of time after the chemical process of resolving thetallow, &c.,into theirelements has been performed before the stearicacid can be obtained; and it will be further seen that the mode ofpreparing the-mass for the hot-pressure is nee-- ing the oleic aciddevolves, cannot properly;

be heated to a higher temperature than 158; otherwise there would be arisk of melting the stearic as well as the oleic acid, which is to beavoided, and the plates, after being heated,have a part of this heatabstracted before it reaches the mixture by the cotton, hair, or hemp incontact with them, and while the heat is thus imperfectly diffusedthroughout the mass the temperature of the steam admitted into the easing for the purpose of keeping the mass hot during pressure, being abouttwo hundred and twelve degrees, (212 is greater than that at which thestearic acid remains solid, and this last therefore is melted at theoutside of the .mass and for a greater or less distance within it. Apart of the stearic acid thus runs ofl' with the oleic, which has to beremanufactured to separate the two. Now, the manner in which I proposeto remedy the objections here suggested is to make the heating moreuniform and perfect,- and thereby accomplish the object in far lesstime, as-follows: I prepare a vat convenient to the press and largeenough to contain easily the mass to be pressed, made up as aforesaid,as if for the cold-pressure. In this vat the mass is entirely surroundedand covered with water. Into the water I introduce steam until the waterand mass are heated to a temperature within that at which stearic acidwill melt,

and varying from eighty to one hundred and thirty degrees, according tothe character of the material used (tallow, for instance, requiring moreheat than lard) and the temperature of the atmosphere. I ascertain theproper heat by the thermometer remaining at the same mark after thesteam is shut ott', for until the whole mass is brought up to theuniform temperature of the surrounding water the thermometer will fallimmediately on the steam being shut off, the mass abstracting the heatfrom the water. As soon as the equilibrium of heat is-establishedbetween the mass throughout and the surrounding water the thermometerwill remain stationary after the steam is shut 0H. A very littleexperience renders this 21. very easy matter to determine when a uniformheat is given to the mass throughout. Where the mass to be pressed is ofthe square already mentioned and four feet high it can be heated in thisway uniformly throughout in from thirty minutes to an hour, according tothe heat of the weather. As soon as the mass is properly and uniformilyheated, as above, it is lifted by a crane and suitable fixtures out ofthe vat and swung round to its place in the press, and the pressureinstantly applied, without jacket, casing, or other contrivance aroundit. The pressure, if done by a hydraulic press of sufficient power, canbe accomplished in fifteen minutes, when the stearic acid will be found,onvopening the mass and removing the coverings, fit to be manufacturedinto candles. Apurer article, still more free from oleic acid, may bemade by a second pressure after remeltin g or regrinding the productfirst obtained. I attribute the facility and quickness with which I thusexpress the oleic acid at one operation-for I dispense altogether withthe cold-pressureto the proper and uniform temperature which I thusimpart to the mass to be pressed before subjecting it to pressure. Theplacing of the mass to be heated in a chamber or vat containing air keptat such a temperature as to heat the mass uniformly th roughout,thoughinferior to the watervat described above, might be made to answer thepurpose in view, and, if used, would be aviolation of my rights, thesubstitution of an aeriform for a liquid medium not affecting theprinciple and modeot'operation ofmyinvention.

What I claim as new, and desire to secure by Letters Patent, is-

The application of heat through a liquid or aeritorm medium to the massto bepressed in such a manner that the said mass, before it is subjectedto pressure, shall be heated gradually and uniformly throughout to sucha degree that, while the stearic acid is at no time during the processmelted, the oleic acid is rendered fluid enough to he afterwardexpressed in the manner above described.

. In testimony whereof I, the said JAMES S. GWYNNE, hereunto subscribemy name in the presence of the witnesses whose names are hereuntosubscribed.

JAS. S. GWYNNE. In presence of-- JNo. H. B. LATROBE, HY. WEBSTER.

